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Mercury Everywhere
It enters the air from manufacturing plants, mining operations and from burning coal and waste. It directly enters the soil and water from the use of some fungicides, the disposal of certain wastes and from natural deposits too.

It rests on our workbenches, rolls onto our floors, sits in our manifolds and spills into the walls of our shops, and mercury-filled, argon tubes dump it into our neighborhoods. So since it’s everywhere, let’s try to understand this surreptitious little inhabitant, mercury, a little better.

Some Facts
Mercury was first separated as an element by French chemist Antoine Laurent Lavoisier. In nature, it generally occurs in compounds combined in the form of sulfides. It’s found in its most pure form with the metal silver and ranks about 67th in abundance among the elements with cinnabar ore producing the most mercury. See Table 1 for more technical information.

ABOUT MERCURY (HG) Atomic number 80 Atomic weight 200 .59 u Bonding radius 1 .49 A Atomic radius 1 .76 A Ionization Potential 10 .437 V Electronegativity 2 Density 13 .53 g/mL Melting point 234 .28K Boiling point 630K Heat of vaporization 59.229 kJ/mol Heat of fusion 2 .295 kJ/mol Specific heat 0 .139 J/gK

Toxicity, Exposure And Risks
We’ve all heard that mercury is dangerous to our health, that its careful use and disposal is not only required, it is mandated. But how many of us heed those warnings? Are these warnings even appropriate? Really, just how dangerous is mercury?

Mercury’s toxicity depends on its chemical state; some forms are even considered non-hazardous. But the most toxic forms are the methylmercury compounds. Dimethyl mercury is strong smelling and boils at 205 degrees Fahrenheit. It is considered one of the most poisonous substances known and can be inhaled or absorbed through the skin. Methylmercury is also the form that builds up in the tissues of fish and other organisms. Its levels generally increase as we move up the food chain.

As a vapor, mercury is extremely dangerous. Allowed to stand open in a poorly ventilated room for long periods, it can affect people regularly occupying that room. Its one reason adequate ventilation is so very important in a neon shop.

Though mercury vaporizes little at room temperature those vapors are readily absorbed into the lungs and distributed by the circulatory system. Some mercury remains in the brain but most is carried to the liver and kidneys where it is laboriously eliminated through bile and urine. Signs of exposure are usually separated into two categories, Acute and Chronic.

Acute exposure may cause chills, nausea, mild sickness or depression, tightness in the chest or chest pains, labored respiration, cough, and inflammation of the mouth, inflammation of the gums, salivation, and diarrhea.

Chronic exposure may cause weakness, prolonged eating disorder, weight loss, and other digestive problems. A tremor beginning in the fingers, eyelids, and lips can spread to the entire body. Behavioral changes include excitability, memory loss, sleeplessness, and depression.

Other chronic symptoms include rashes, excessive sweating, severe salivation, fever, and painful peeling of the skin on the hands and feet. Long-term damage to the kidneys, the immune and/or nervous system even death can result from chronic exposure.

Ingested mercury is not safe either. Small amounts repeatedly ingested over long periods of time can cause irreversible brain, liver and kidney damage and even unwanted reproductive effects.

Limiting Exposure
Mercury vapor is colorless and odorless; you won’t see or smell it coming. So, adequate ventilation is the simplest precaution against long-term exposure.

The Occupational Safety and Health Administration (OSHA) determines a worker's exposure to airborne mercury vapor by collecting air samples and analyzing them. Their ceiling limit of permissible exposure is 0.1 milligram per cubic meter of air. The National Institute sets exposure limit per workday and workweek for Occupational Safety and Health.

Proper mercury handling is your next best precaution. Make certain all mercury containers are well sealed and that all spills are collected using an acceptable mercury collection system.

Check with your local sign supply distributor or local scientific equipment supply house to locate mercury spill cleanup kits. These systems vary widely in price and application so shop around.

A simple sponge is designed for micro-droplet cleanup and can cost well under fifty dollars. A powder that absorbs larger droplets and changes color in the presence of mercury usually costs less than forty dollars. But an industrial size emergency cleanup kit that can clean up several liters of mercury will cost as much as five hundred dollars and is likely overkill for use in a typical neon shop.

Medical Surveillance
Currently, OSHA is developing medical surveillance and procedure guidelines. They will be used to determine whether employees exposed to mercury vapor are required to utilize the following and other medical procedures.

Preplacement medical evaluations would consider the potential for mercury vapor exposure and document initial baseline, health status. Systematic follow-up healthcare interviews and tests would help to prevent occupational injury and disease.

The program may include mandated Federal, State or local standards or where none exist, recommend evaluations every three to five years. Tests of urine and blood may be included to determine biological exposure. Doctors may also test scalp hair to measure exposure to methyl mercury.

Reporting Spills
OSHA states, “Reportable quantity requirements for hazardous releases. A hazardous substance release is defined by EPA as any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment (including the abandonment or discarding of contaminated containers) of hazardous substances. In the event of a release that is above the reportable quantity for that chemical, employers are required to notify the proper Federal, State, and local authorities [40 CFR 355.40].”

Now, they also state, “The reportable quantity of mercury is 1 pound. If an amount equal to or greater than this quantity is released within a 24-hour period in a manner that will expose persons outside the facility, employers are required to do the following: - Notify the National Response Center immediately at (800) 424-8802 or at (202) 426-2675 in Washington, D.C. [40 CFR 302.6].”

This means that the typical, small mercury spill contained in a neon shop does not require reporting to the National Response Center. However, as I have witnessed, some sign shop personnel actually dump bottles of dirty mercury into storm sewer drains. This is not acceptable! It pollutes our waterways and sea animals and works its way up the food chain into people. It may also invite unwanted regulation and enforcement. So, what to do?

A Better Solution On the Horizon?
Recently, I received a phone call from a fellow craftsman. He pointed out a new product coming to market called, Quicksilver ­ The Neon Electrode With Mercury Built-In. It’s manufactured by Masonlite, Ltd., 36 second Avenue, Chatham, Kent ME4 5AX or in the United States, Masonlite, Ltd., 35 Lumber Road, Roslyn, NY 11578.

Their literature claims “…it removes mercury from the workroom. No open bottles or spillages.” You process and age a typical mercury-filled tube using the electrode’s two outside wires. Upon tube process completion and cooling, you connect the center dumet wire to a transformer rated 60 millamperes or higher. After about four seconds, a bright blue glow appears indicating the insertion of mercury.

Pretty slick if it works and just might be the solution to all our neon shop mercury hazard fears. Only time and the marketplace will tell for sure.

In Conclusion
What does this all mean to your typical neon shop? First, consider mercury a toxic substance and second, safely store and collect it. Third, follow guidelines put forth by leading health and safety organizations and finally, keep your eyes peeled for better ways to handle mercury or introduce it into your product because being unsafe with mercury carries too high a price to be ignored.